Raltegravir (MK-0518) is an HIV-1 integrase inhibitor with potent in vitro activity against HIV-1 strains including those resistant to currently available antiretroviral drugs. The purpose of this study is to assess the effectiveness of raltegravir in further reducing viral load in HIV infected patients that have already achieved viral suppression below the level of detection of standard viral load assays when added to antiretroviral therapy (ART).

HIV-1 RNA level, as measured by single copy assay, averaged at weeks 10 and 12. The quantification limit of single copy assay was determined by the volume of plasma tested. When averaging the week 10 and 12 measurements, if one of both measurements were below the single copy assay lower limits, the lower limit of quantification was used to compute the average and the result was treated as below the averaged value.

Change in HIV-1 RNA level, as measured by single copy assay, from baseline to weeks 10/12 . When averaging the measurements at pre-entry and entry, and at weeks 10 and 12, measurements below the lower limit of quantification (LLQ) were imputed a value of the LLQ divided by 2.

Change in Total CD4 Cell Count [ Time Frame: At pre-entry, entry, and week 12 ] [ Designated as safety issue: No ]

CD4 cell counts were assessed by flow cytometry at pre-entry and entry (the baseline value was the average of the two measurements) and at week 12

Change in Total CD8 Cell Count [ Time Frame: At pre-entry, entry, and week 12 ] [ Designated as safety issue: No ]

CD8 cell counts were assessed by flow cytometry at pre-entry and entry (the baseline value was the average of the two measurements) and at week 12

Level of CD4+ T-cell activation was determined by measuring the percentage of cells that expressed both the activation marker CD38 and Human leukocyte antigen (HLA)-DR. Levels measured at pre-entry and entry were averaged. Change from baseline to week 12 was defined as CD4+/CD38+/HLA-DR+% at week 12 minus CD4+/CD38+/HLA-DR+% at baseline.

Level of CD8+ T-cell activation was determined by measuring the percentage of cells that expressed both the activation marker CD38 and Human leukocyte antigen (HLA)-DR. Levels measured at pre-entry and entry were averaged. Change from baseline to week 12 was defined as CD8+/CD38+/HLA-DR+% at week 12 minus CD8+/CD38+/HLA-DR+% at baseline.

Number of Participants Who Experienced Study Related Grade 2 or Higher Signs/Symptoms, Grade 3 or Higher Laboratory Abnormalities and Clinical Events From First Day of Treatment to Week 12 [ Time Frame: From first day of treatment to week 12 ] [ Designated as safety issue: Yes ]

Participant who experienced at least one study related grade 2 or higher signs/symptoms, grade 3 or higher laboratory abnormalities and clinical events that are "possibly", "probably" or "definitely" related to study treatment. DAIDS Toxicity Grading Table (2004) was used for grading.

Although ART has reduced the morbidity and mortality from HIV-1 infection, most individuals who stop ART experience rapid viral rebound. Effective ART can suppress viral load to less than 50 copies/ml; however, current treatment regimens cannot completely eliminate the infection. The primary purpose of this study was to assess the ability of the HIV-1 integrase inhibitor, raltegravir, to reduce viral load when added to ART regimens of HIV-1 infected patients who have achieved viral suppression to less than 50 copies/ml.

The study lasted 24 weeks. Participants were randomly assigned to one of two arms. Participants in Arm A were administered raltegravir in addition to their usual ART regimen from study entry until Week 12. At Week 12, subjects halted raltegravir use and received a placebo until Week 24. Participants in Arm B were administered the placebo in addition to their usual ART regimen from study entry until Week 12. At Week 12, subjects halted the placebo and received raltegravir until Week 24. A real-time polymerase chain reaction (PCR) single copy assay (SCA) capable of detecting 1 copy of HIV RNA was used to assay viral load. The cross-over design allowed assessment of the effect of intensification with raltegravir between the two arms at Weeks 10/12 and every participant enrolled in the study receiving raltegravir for 12 weeks. Primary analysis focused on weeks 10/12 measurement and with no washout period, typical analysis of cross-over design was not intended.

All participants had scheduled visits at Weeks 0, 2, 4, 10, 12, 14, 16, 22, and 24. A targeted physical exam occurred at all visits. Blood and urine collection occurred at selected visits. A medical/medication assessment occurred at trial entry. Drug dispensing and an adherence questionnaire occurred at some visits. A pregnancy test occurred at select visits. Participants' background ART medications were not provided by the study.

Eligibility

Ages Eligible for Study:

18 Years and older

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

HIV-1 Infection

ART for at least 12 months prior to study entry that includes at least two NRTIs and either an NNRTI or a ritonavir-boosted PI

No change in ART regimen for at least 3 months prior to study entry

CD4 count of 200 or more at screening

Viral load below the limit of quantification of an ultrasensitive assay for at least 6 months prior to study entry

Viral load less than 50 copies/ml using Roche Amplicor HIV-1 RNA Ultrasensitive assay within 60 days of study entry

All viral load assays obtained within 6 months prior to study entry lower than limits of quantification on all tests

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00515827